/Engine/Source/Developer/DesktopPlatform/Public/IDesktopPlatform.h
Opens the "choose folder" dialog for the platform
true if folder choice was successfully selected
bool OpenDirectoryDialog ( const void * ParentWindowHandle, const [FString](API\Runtime\Core\Containers\FString) & DialogTitle, const [FString](API\Runtime\Core\Containers\FString) & DefaultPath, [FString](API\Runtime\Core\Containers\FString) & OutFolderName )